Aqueous polyurethane dispersions derived from polycarbonatediols

Aqueous polyurethane dispersions derived from polycarbonatediols, isophorone diisocyanate, and carboxylic diols including dimethylol propionic acid and dimethylol butyric acid were prepared. The effect of dispersing procedure is investigated by FT IR, GPC, and the tensile film properties. The polyurethane dispersions prepared by a standard procedure exhibit lower molecular weights due to the overhydrolysis of the NCO groups. The polyurethane dispersions prepared by a modified procedure exhibit significantly higher molecular weights due to more effective chain extension, and their cast films exhibit higher tensile strength. The particle size, tensile properties, thermal properties, and dynamic mechanical properties are investigated. The chemical structure of the polycarbonatediols seems to affect the tensile strength. The glass transition temperature of the soft segments, T_g(S), of the polyurethane dispersions can be seem from the DSC and DMA data. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1723–1729, 2004     

Polyurethane dispersions derived from polycarbonatediols and m‐di(2‐isocyanatopropyl)benzene

Aqueous polyurethane dispersions derived from various polycarbonatediols, m‐di(2‐isocyanatopropyl)benzene(TMXDI), and various carboxylic diols including dimethylol propionic acid (DMPA), dimethylol butyric acid (DMBA), and a carboxylic polycaprolactonediol (Placcel 205BA) were prepared by a method in which the dispersing procedure was modified to enhance the molecular weight. The NH₂/NCO ratio during chain extension affected the molecular weight of the polyurethanes, significantly, and an optimum ratio of 0.67:1.0 was used. The molecular weight, particle size, tensile properties, and thermal properties of the polyurethane dispersions were investigated. The effect chemical structure of the polycarbonatediols on the properties shows no obvious trend, but the polyurethane dispersions derived from the carboxylic polycaprolactonediol exhibit smaller particle size and softer tensile properties when compared with those derived from DMPA and DMBA. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Aqueous polyurethane dispersions derived from polycarbonatediols and Di(4‐isocyanatocyclohexyl)methane

Aqueous polyurethane dispersions derived from various polycarbonatediols, di(4‐isocyanatocyclohexyl)methane (HMDI), and various carboxylic diols, including dimethylol propionic acid (DMPA), dimethylol butyric acid (DMBA), and a carboxylic polycaprolactonediol, were prepared by a method in which the dispersing procedure was modified to enhance the molecular weight. The molecular weight, particle size, tensile properties, thermal properties, and dynamic mechanical properties of the polyurethane dispersions were investigated. The dynamic mechanical property data indicate that these polyurethane dispersions can exhibit higher temperature resistance when compared with those derived from isophorone diisocyanate (IPDI). POLYM. ENG. SCI. 46:588–593, 2006. © 2006 Society of Plastics Engineers     

Thermally stable polyurethane‐ureas and copolyurethane‐ureas containing zinc and nickel dihydroxysaltrien complexes

New 4,4′‐dihydroxysaltrien metal complexes, (MOHSal₂trien, where M = Zn and Ni) were synthesized and used for the synthesis of metal‐containing polyurethane‐ureas and copolyurethane‐ureas. MOHSal₂trien underwent polymerization reaction with two diisocyanates, namely 4,4′‐diphenylmethane diisocyanate (MDI) and isophorone diisocyanate (IPDI) to yield polyurethane‐ureas. Copolyurethane‐ureas were synthesized by the reaction between MOHSal₂trien, MDI, and diamines or dialcohols. The diamines or dialcohols employed were 4,4′‐methylenedianiline (MDA), hexamethylenediamine (HMA), bisphenol A (BPO), and hexamethylene glycol (HMO). The polymers were characterized by IR, NMR, elemental analysis, XRD, solubility, and viscosity. Thermal stability and flammability of polymers were studied by thermogravimetric analysis (TGA) in air and by measuring limiting oxygen index (LOI) values, respectively. It was found that the resulting metal‐containing polyurethane‐ureas and copolyurethane‐ureas exhibited good thermal stability. Among all metal‐containing polyurethane‐ureas, NiOHSal₂trien‐MDI was the most thermally stable polymer with char yield of 55% at 600°C. Solubility in DMSO of zinc‐containing copolyurethane‐ureas based on dialcohols was greatly improved when compared with those of zinc‐ and nickel‐containing polyurethane‐ureas. ZnOHSal₂trien‐MDI‐BPO and ZnOHSal₂trien‐MDI‐HMO gave high char yield of 46% at 600°C, which is almost comparable with that of NiOHSal₂trien‐MDI. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation of silicon dioxide/polyurethane nanocomposites by a sol–gel process

Aqueous emulsions of cationic polyurethane ionomers, based on poly(?‐caprolactone glycol) as soft segment, isophorone diisocyanate as hard segment, 3‐dimethylamino‐1,2‐propanediol as chain extender and potential ionic center, and hydrochloric acid as neutralizer, were mixed with tetraethoxysilane to prepare silicon dioxide–polyurethane (SiO₂/PU) nanocomposites by a sol–gel process during which the inorganic mineral is deposited in situ in the organic polymer matrix. The sizes and distributions of the particles were measured by dynamic light scattering, and the structure and morphology of the nanocomposites were observed by transmission electron microscope and FTIR spectrum. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2013–2016, 2004     

Preparation and properties of waterborne polyurethane–urea anionomers. I. The influence of the degree of neutralization and counterion

Two series of waterborne polyurethane–urea anionomers were prepared by a polyaddition reaction with isophorone diisocyanate, poly(tetramethylene oxide) glycol (weight‐average molecular weight = 1000), dimethylol propionic acid (DMPA), and ethylene diamine as chain extenders. Triethylamine (TEA) or 28:1 mol/mol ammonium hydroxide (NH₄OH)/cupric hydroxide [Cu(OH)₂] was used as a neutralization agent [NH(C₂H₅) or NH/Cu²⁺ counterion] for the pendant COOH group of DMPA. The effects of the degree of neutralization and counterion on the particle size of the dispersions, the conductivity, and the antibacterial and mechanical properties of polyurethane–urea anionomer films were investigated. The particle sizes of the two sample series dispersions decreased with an increasing degree of neutralization. Aqueous dispersions of polyurethane–urea anionomers with particle sizes of 30–120 nm were stable for about 3 months. By infrared spectroscopy, it was found that TEA‐based samples (T series) had higher fractions of hydrogen‐bonded carbonyl groups in the ordered region than NH₄OH/Cu(OH)₂‐based samples (S series). However, the fractions of hydrogen‐bonded carbonyl groups in the disordered region of the S‐series samples were higher than those of the T‐series samples. The conductivities of the S‐series film samples were higher than those of the T‐series samples. However, the T‐series film samples commonly had higher tensile strengths and initial moduli than the S‐series samples. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2375–2383, 2002     

Fluorinated segmented polyurethane anionomers for water–oil repellent surface treatments of cellulosic substrates

Three model structures of linear segmented anionomeric polyurethanes based on perfluoropolyether dimethylol‐terminated oligomers, isophorone diisocyanate, and dimethylol propionic acid were synthesized and obtained in the form of aqueous dispersions. The structures differed from each other in the chemical nature of the chain extender (diol or diamine) and in the content of carboxylic acid. Dispersions and polymer films were characterized by dynamic light scattering, dynamic mechanical analysis, differential scanning calorimetry, and contact angle measurements. Diluted aqueous dispersions were also evaluated as protective sizing agents in paper treatment, both as bulk modifiers and as surface treatments. Paper sheets characterized by high water and oil repellence were obtained. The results showed that performance is mainly related to the ionic group content of the polymer and to its molecular architecture. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1364–1372, 2005     

Synthesis and properties of block and graft waterborne polyurethane modified with α,ω‐bis(3‐(1‐methoxy‐2‐hydroxypropoxy)propyl)polydimethylsiloxane and α‐N,N‐dihydroxyethylaminopropyl‐ω‐butylpolydimethylsiloxane

In this study, α,ω‐bis(3‐(1‐methoxy‐2‐hydroxypropoxy)propyl)polydimethylsiloxane and α‐N,N‐dihydroxyethylaminopropyl‐ω‐butylpolydimethylsiloxane were used to prepare block and graft waterborne polyureathane–polysiloxane copolymer dispersions. α,ω‐bis(3‐(1‐methoxy‐2‐hydroxypropoxy)propyl)polydimethylsiloxane was synthesized by hydrosilylation, methoxylation and equilibrium reactions; α‐N,N‐dihydroxyethylaminopropyl‐ω‐butylpolydimethylsiloxane was synthesized via hydroxyl protection, alkylation, anionic ring‐opening polymerization, hydrosilylation, and deprotection. Block and graft waterborne polyurethane–polysiloxane copolymer dispersions were prepared by the reaction of poly(propylene glycol) (PPG), toluene diisocyanate (TDI), 2,2‐dimethylol propionic acid (DMPA), 1,4‐butanediol (BDO), α,ω‐bis(3‐(1‐methoxy‐2‐hydroxypropoxy)propyl)polydimethylsiloxane, and α‐N,N‐dihydroxy‐ethylaminopropyl‐ω‐butylpolydimethylsiloxane. The water absorption of block and graft waterborne polyurethane–polysiloxane copolymer films decreased from 163.9 to 40.2% and 17.3%, respectively, when percent of polysiloxane (w/w) increased from 0 to 5%, and the tensile strength of the block waterborne polyurethane–polysiloxane copolymer films decreased while the tensile strength of graft waterborne polyurethane–polysiloxane copolymer films increased with increase of percent of polysiloxane. For graft waterborne polyurethane–polysiloxane films, the tensile strength would decrease when percent of polysiloxane was more than 3%. POLYM. ENG. SCI., 54:805–811, 2014. © 2013 Society of Plastics Engineers     

Polyurethane ionomer dispersions from a blocked aromatic‐diisocyanate prepolymer

Aqueous anionic blocked aromatic polyurethane prepolymers were synthesized by a prepolymer mixing process and their dispersions were obtained by adding water to the blocked prepolymer solutions. A series of prepolymers were prepared by using toluene 2,4‐diisocyanate, 4,4′‐diphenylmethane diisocyanate, polytetramethylene glycol, dimethylol propionic acid, methyl ethyl ketoxime and ε‐caprolactam. The aqueous dispersions were characterized by Fourier‐transform infrared spectroscopy, gel permeation chromatography, differential scanning calorimetry and thermogravimetric analysis. The particle sizes, viscosities, pH and storage stabilities of the dispersions were studied and compared. Some mechanical properties of the cast films obtained from the aqueous dispersions and the adhesive properties of the dispersions were also evaluated. Copyright © 2004 Society of Chemical Industry     

Effects of TDI and FA‐703 on physico‐mechanical properties of polyurethane dispersion

A series of water dispersion polyurethanes dispersions (PUDs) were prepared by polyaddition reaction using isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), poly(oxytetramethylene) glycol (PTMG), dimethylol propionic acid (DMPA), and triol (trade name FA‐703). Various formulations were designed to investigate the effects of process variables such as TDI and FA‐703 on the physico‐mechanical properties of PUD. IR spectroscopy was used to check the end of polymerization reaction and characterization of polymer. Evolution of the particle size distribution, contact angle, T_g, molecular weight, viscosity, and mechanical properties of the emulsion‐cast films were significantly affected by variable content of TDI and FA‐703. Average particle size of the prepared polyurethane emulsions and contact angle decrease with increase of content of FA‐703 and TDI. Molecular weight, T_g, tensile strength, tear strength, hardness, viscosity and elongation at break increase with increase of content of FA‐703 and TDI. The increase of molecular weight, tensile strength, tear strength and elongation at break properties are interpreted in terms of increasing hard segments, chain flexibility, and phase separation in high content of FA‐703 and TDI‐based polyurethane. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Interfacial behavior of epichlorohydrin–ethyleneoxide–allylglycidyl ether/fluorinated carbon black observed from mechanical and dielectrical properties

The purpose of this work was to study the effect of carbon black (CB) surface state on the interaction between CB and polymer matrix, as well as the polymer chain mobility. The mobility of polymer chain absorbed on the CB surface was estimated by using a dynamic mechanical analyzer and an impedance analyzer. The interaction parameter (B) and immobilized polymer layer thickness (ΔR) were estimated from the dynamic mechanical analysis. It was observed that values of B and ΔR decreased with increasing fluorine content on the CB surface. On the other hand, from the dielectric measurement, the Maxwell–Wagner–Sillars (MWS) relaxation peak, accompanied by migration of the charge carriers, accumulated at the interface between polymer and CB, observed at temperatures higher than the glass‐transition temperature (T_g) of the polymer matrix. The activation energy (E_{a MWS}), calculated from the relaxation frequency of MWS relaxation, was decreased with increasing surface fluorine content. Good agreement was found between the B and the ΔR values estimated from the dynamic mechanical analysis and the E_{a MWS} calculated from the MWS relaxation frequency estimated from dielectric measurement. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2928–2933, 2004     

The chain extension of anionic prepolymers in the preparation of aqueous poly(urethane–urea) dispersions

Anionic polyurethane prepolymers end‐capped with isocyanate groups were dispersed and chain‐extended in aqueous media using three different extension agents: hydrazine, 1,2‐ethylene diamine (EDA) and 1,2‐propylene diamine (PDA). Two types of prepolymer were used. The first was prepared from isophorone diisocyanate (IPDI), α,α‐dimethylol propionic acid (DMPA) and poly(propylene oxide) diol (PPO) and the second from α,α,α′,α′‐tetramethyl‐1,3‐xylylene diisocyanate (m‐TMXDI), poly(caprolactone) diol (PCL) and DMPA. The colloidal particles which formed in the dispersion process and the constituent poly(urethane–urea) chains were characterised by a combination of dynamic and static light scattering, gel permeation chromatography and FTIR spectroscopy. Using EDA as the extender, a study was made of how the degree of extension depended on the molar ratio of amine to isocyanate groups, [NH₂]/[NCO] (= R_{A, I}). It was found that using a stoichiometric balance of isocyanate and amine groups did not lead to high degree of extension, and better chain extension was obtained at lower R_{A, I} values. In a comparative study using stoichiometric balances of isocyanate and amine groups, the degrees of extension obtained using PDA and EDA were approximately the same, while hydrazine was the least effective. Force–extension studies were carried out on samples prepared from films cast from the aqueous poly(urethane–urea) dispersions in order to assess the influence of chain‐extender type and stoichiometry on bulk properties; values of Young's modulus, tensile strength and maximum extension are reported. Copyright © 2003 Society of Chemical Industry     

Synthesis and characterization of high solid content aqueous polyurethane dispersion

Aqueous polyurethane (APU) dispersions having a solid content of 50% were synthesized using dimethyol propionic acid (DMPA) as the stabilizing moiety. The principal diols used were poly‐1,4‐butylene adipate glycol (PBA). The diisocyanates used in this study were a 30:70 blend of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI). All these samples were neutralized using triethylamine (TEA) and chain‐extended using ethylene diamine (EDA). The effects of the COOH content, NCO/OH molar ratio, and molecular weight (M_n) of PBA on the properties of APU dispersion and its cast film were studied. Dynamic light scattering results revealed that these high solid content dispersions shown broad particle size distributions as well as bimodal. Differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMA) results showed that as the hard segment content increased, the melting point (T_m) of the APU cast film increased, but the glass transition temperature (T_g) did not show significant alteration, when a PBA lower than 1000 M_n was used, the APU exhibited faint soft‐segment crystallization and tended to form amorphous polymer. Tensile and T‐peel strength tests attained excellent mechanical properties, such as a maximum Young's modulus of 166 MPa and the elongation at break reached to 2000%. T‐peel strength test (PVC/PVC) yielded a maximum peel strength value of 8.8 N/mm. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Modification of aqueous polyurethane dispersions via tetraphenylethane iniferters

Aqueous polyurethane (PU) dispersions containing tetraphenylethane iniferter groups were prepared from 4,4′‐diphenylmethane diisocyanate, poly(propylene oxide)glycols, dimethylol propionic acid, and 1,1,2,2‐tetraphenylethane‐1,2‐diol. To improve the water resistance of the dispersions, methyl methacrylate monomers were added into these dispersions and block‐copolymerized onto the main PU chain. The viscosity and particle size of the dispersions were determined. Dispersion‐cast films were characterized in terms of the contact angle, the swell in water, and the mechanical properties. Contact‐angle and water‐swell measurements showed that the hydrophilicity of the films was decreased significantly when methyl methacrylate was polymerized in the presence of tetraphenylethane containing aqueous PU dispersions. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2993–3000, 1999     

Preparation and properties of waterborne polyurethane/polyaniline codoped with dodecyl benzene sulfonic acid and hydrochloric acid blends

A conductive poly(aniline codoped with dodecyl benzene sulfonic acid and hydrochloric acid) [PANI‐D/H, yield: 32.2%, intrinsic viscosity ([η]): 1.39 dL/g, electrical conductivity: 7.3 S/cm] was synthesized by chemical oxidative polymerization from aniline‐dodecylbenzene sulfonic acid salt (A‐DS)/aniline‐hydrochloric acid salt (A‐HS) (6/4M ratio) in an aqueous system. Waterborne polyurethane (WBPU) dispersion obtained from isophorone diisocyanate/poly(tetramethylene oxide)glycol/dimethylol propionic acid/ethylene diamine/triethylene amine/water was used as a matrix polymer. The blend films of WBPU/PANI‐D/H with various weight ratios (99.9/0.1–25/75) were prepared by solution blending/casting. Effect of PANI‐D/H content on the mechanical property, dynamic mechanical property, hardness, electrical conductivity, and antistaticity of WBPU/PANI‐D/H blend films was investigated. The dynamic storage modulus and initial tensile modulus increased with increasing PANI‐D/H content up to 1 wt %, and then it was significantly decreased about the content. With increasing PANI‐D/H content, the glass transition temperature of soft segment (T_gs) and hard segment (T_gh) of WBPU/PANI‐D/H blend films were shifted a bit to lower the temperature. The tensile strength and hardness of WBPU/PANI‐D/H blend films increased a little with increasing PANI‐D/H content up to 0.5 wt %, and then it was dramatically decreased over the content. The elongation at break of WBPU/PANI‐D/H decreased with an increase in PANI‐D/H content. From these results, it was concluded that 0.5–1 wt % of PANI‐D/H was the critical concentration to reinforce those various properties of WBPU/PANI‐D/H blend films prepared in this study. The electrical conductivity of WBPU/ultrasonic treated PANI‐D/H (particle size: 0.7 μm) blend films prepared here increased from 4.0 × 10^?7 to 0.33 S/cm with increasing PANI‐D/H content from 0.1 to 75 wt %. The antistatic half‐life time (τ_1/2) of pure WBPU film was about 110 s. However, those of WBPU/ultrasonic treated PANI‐D/H blend films (τ_1/2: 8.2–0.1 s, and almost 0 s) were found to decrease exponentially with increasing PANI‐D/H content (0.1–9 wt %, and above 9 wt %). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 700–710, 2004     

Dry‐peelable temporary protective coatings from waterborne self‐crosslinkable sulfourethane–silanol dispersions

Novel temporary protective coatings were prepared by the addition of release additives to waterborne polyurethane dispersions. New types of self‐crosslinkable sulfourethane–silanol (SUS) dispersions were utilized as the peelable coatings. These dispersions are stable, low‐volatility organic chemical (VOC) waterborne dispersions that spontaneously crosslink upon drying without extra additives or processing steps. Tensile strengths up to 6000 psi with elongations between 300–600% were obtained for the crosslinked films. The adhesion of the films to a variety of substrates can be controlled by the addition of hydrophilic additives, including glycerol, oligomers of glycerol, and poly(ethylene glycol) derivatives. Alternatively, hydrophobic additives that are water dispersible, such as paraffin waxes and sulfated castor oil, can also be used to control adhesion. In addition, this technique can be utilized for the release of films derived from a wide variety of waterborne urethane dispersions, including carboxylated polyurethane ureas. The removable coatings are useful for the temporary protection of plastic surfaces during thermoforming processes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1443–1449, 2004     

Effects of the reagent molar ratio on the phase separation and properties of waterborne polyurethane for application in a water‐based ink binder

Waterborne polyurethane (WPU) dispersions with a high solid content and low viscosity were prepared successfully by a two‐step polymerization with isophorone diisocyanate, poly(propylene glycol), and dimethylol propionic acid as the main raw materials. The molar ratio of hard segments to soft segments was controlled to investigate its influence on the particle size, particle morphology, stability of dispersions, and final properties of the WPU films. Measurements including attenuated total reflectance/Fourier transform infrared spectroscopy, transmission electron microscopy, differential scanning calorimetry, thermogravimetric analysis, X‐ray diffraction, polarizing optical microscopy, and contact angle tests were used to characterize the bulk structures, phase separation, thermal stability, crystallinity, and wettability of the WPU dispersions. The results indicate that all of the WPU dispersions with a high solid content (ca. 40 wt %) and low viscosity (ca. 20–50 mPa s) displayed excellent stability. The prepared WPU dispersions with acetone contents of 5–7 wt % could be used directly as an ink binder without removing the acetone; this is beneficial to industrial applications of water‐based ink binders. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45406.     

Preparation and colloidal properties of an aqueous acetic acid lignin containing polyurethane surfactant

Aqueous acetic acid lignin containing polyurethane (ALPU) surfactants were prepared by the replacement of some hydrophobic poly(caprolactone diol) with different concentrations of multifunctional acetic acid lignin (AL), and with dimethylol propionic acid as the hydrophilic segment. The infrared spectra, together with thermogravimetric analysis, demonstrated the presence of AL in the polyurethane (PU) chains. In addition, the effects of the AL concentration on the particle size, morphology, rheological behavior, and surface activity of the dispersions were investigated. The ALPU particles displayed a spherical morphology. With increasing AL concentration from 0 to 10 wt %, the particle size increased from 36 to 260 nm, and the unimodal distribution was detected for ALPU₁₀ with a 10 wt % AL addition. The viscosity and shear‐thinning behavior of the ALPU dispersions decreased, and the lowest surface tension and critical micelle concentration (cmc) were detected for ALPU₁₀. However, when the AL concentration was 15 wt % (ALPU₁₅), the surface tension and cmc increased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1855–1862, 2013     

Aqueous poly(urethane–urea) dispersions and cast films based on m‐TMXDL. 1. Structure–property relationships

Aqueous poly(urethane–urea) dispersions were prepared from polycaprolactone diol, α,α,α′,α′‐tetramethyl‐1,3‐xylylene diisocyanate (m‐TMXDI) and α,α‐dimethylol propionic acid (DMPA) using a prepolymer mixing process. In the process, polyurethane prepolymers were neutralised with triethylamine and the chains extended in water with either hydrazine, 1,2‐ethylene diamine or 1,2‐propylene diamine. For comparison, some samples were prepared from a more commonly used diisocyanate, isophorone diisocyanate (IPDI). Dispersion characteristics and basic structure–property relationships of the cast films were determined. m‐TMXDI provided some advantages over IPDI in the preparations since its use gave lower prepolymer viscosities and better resistance to elevated temperatures. Films prepared from m‐TMXDI dispersions exhibited considerably lower values of Young's modulus and hardness and higher elongations at break than those prepared from IPDI‐based dispersions for analogous compositions, whereas differences in the average particle sizes or viscosities of the dispersions were only small. When the DMA content was varied, the dispersions and cast films of m‐TMXDI‐based systems showed similar changes as are known to occur in IPDI‐based systems: as the DMPA content was increased, the average particle size of the dispersions decreased and the viscosity increased, and for the cast films, the Young's modulus and tensile strength increased and the maximum elongation at break decreased. Changing the chain‐extension agent from hydrazine to 1,2‐ethylene diamine, to 1,2‐propylene diamine and had little effect on the particle size of the dispersions, but increased the Young's modulus and hardness of the respective cast films. Molar masses of the chain‐extended polymers were unexpectedly low. DSC analysis of cast films indicated that the degree of crystallisation of the soft or hard domains was low. © 2002 Society of Chemical Industry     

Kinetic investigations of acrylic–polyurethane composite latex

The effect of various reaction parameters on the rate of polymerization, R_p, and on the particle size and morphology of aqueous acrylic–polyurethane hybrid dispersions, prepared by semibatch emulsion polymerization, was investigated. The particles of polyurethane dispersion were used as seeds during the polymerization of acrylic component: methyl methacrylate (MMA), butyl acrylate (BA), and a mixture of MMA and BA with the ratio of 1:1. These emulsions were found to form structured polymer particles in aqueous media using scanning electron microscopy. The kinetics of the emulsion polymerization was studied on the basis of Wessling's model. The influence of emulsifier and initiator concentrations, including the monomer feed rates, R_m, on the rates of polymerization and on the properties of the resulting dispersions were studied. The number of particles and the particle size were also measured during the polymerization process. The final values were found to be independent of the concentration of the emulsifier, initiator and the monomer feed rate in monomer starved conditions. In the steady‐state conditions, during the seeded semibatch hybrid emulsion polymerization, the rate of polymerization and the monomer feed rate followed the Wessling relationship 1/R_p = 1/K + 1/R_m. The dispersions MMA/PU, BA/PU, and MMA/BA/PU have K values of 0.0441, 0.0419 and 0.0436 mol/min, respectively. The seeded BA/PU hybrid polymerization proceeded according to Smith‐Ewart Case I kinetics, while the MMA/PU hybrid emulsions demonstrate Case II of the Smith‐Ewart kinetic model. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2639–2649, 2002